“We present ABACuS, a new low-cost, hardware-based RowHammer mitigation technique that scales in a performance-, energy-, and area-efficient manner with the increasing RowHammer vulnerability. We observe that both benign workloads and RowHammer attacks tend to access DRAM rows with the same row address in multiple DRAM banks at approximately the same time. Based on this observation, the key idea of ​​ABACuS is to use a single common row activation counter to track activations of the rows with the same row address in all DRAM banks. Unlike state-of-the-art RowHammer mitigations that implement a separate row activation counter for each DRAM bank, ABACuS implements fewer counters (e.g., only one) to track an equal number of attacker rows.

Our extensive evaluations show that ABACuS safely prevents RowHammer bitflips at low power/energy overhead and low area cost. We compare ABACuS to four state-of-the-art mitigation mechanisms. At a near-future RowHammer threshold of 1000, ABACuS incurs only 0.58% (0.77%) power and 1.66% (2.12%) DRAM energy overhead averaged over 62 single-core workloads (8 cores) and requires only 9.47 KiB of memory per DRAM rank. At the RowHammer threshold of 1000, the best mitigation mechanism to date with low area cost incurs 1.80% higher average power overhead than ABACuS, while ABACuS requires 2.50x less chip area to implement. At a future RowHammer threshold of 125, ABACuS performs very similarly (within 0.38% of the performance) to the best power and energy efficient RowHammer mitigation mechanism to date, while using 22.72 times less chip area. We show that the performance of ABACuS scales well with the number of DRAM banks. At the RowHammer threshold of 125, ABACuS incurs performance degradations of 1.58%, 1.50%, and 2.60% for 16-, 32-, and 64-bank systems on all single-core workloads. ABACuS is free and openly available at https://github.com/CMU-SAFARI/ABACuS.”

The technical document can be found here.

Olgun, Ataberk, Yahya Can Tugrul, Nisa Bostanci, Ismail Emir Yuksel, Haocong Luo, Steve Rhyner, Abdullah Giray Yaglikci, Geraldo F. Oliveira, and Onur Mutlu. “Abacus: All-bank activation counters for scalable and low-cost Rowhammer mitigation.” In USENIX Security. 2024.

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